1-Bromopropane based fluids have found widespread use in industry for uses such as solvent cleaning, i.e. vapor degreasing, cold cleaning and ultrasonic cleaning of complex metal parts, circuit boards, electronic components, implantable prosthetic devices, optical equipment and others.
For difficult to remove soils where elevated temperature is necessary to improve the cleaning action of the solvent, or for large volume assembly line operations where the cleaning of metal parts and assemblies must be done efficiently, a vapor degreaser is employed. In its simplest form, vapor degreasing, consists of exposing a room temperature object to be cleaned to the vapors of a boiling solvent. Vapors condensing on the object provide clean distilled solvent to wash away grease or other contaminants. Final evaporation of the solvent from the object leaves no residue on the object.
Azeotropic or azeotrope-like solvent compositions are particularly desired because they do not fractionate upon boiling. This behavior is desirable because in the previously described vapor degreasing equipment, in which such solvents are employed, redistilled solvent is generated for final rinse cleaning. Thus, the vapor degreasing system acts as a still. Unless the solvent composition exhibits a constant boiling point, i.e., is azeotrope-like, fractionation will occur and undesirable solvent distribution may upset the cleaning and safety of the process.
Azeotropic mixtures of 1-bromopropane are also advantageous in the foam blowing industries. In foam blowing applications 1-bromopropane suffers from the disadvantage in that it is too aggressive a solvent and results in considerable shrinkage of foam in foam blowing applications. Mixtures comprised of less aggressive solvents, in particular azeotropic mixtures, can be used to offset this disadvantage.
Azeotropic mixtures are also advantageous in systems where various materials are dissolved in the solvent mixture and deposited on a substrate upon evaporation of the solvent. Such systems include paints, coatings, adhesives, and lubricants. Azeotropes are preferred for such systems since the solubility parameters of the solvent system remains relatively constant as the azeotrope evaporates.
The art is continually seeking new solvent mixtures that have improved properties for the above-described applications. Currently, environmentally acceptable materials are of particular interest because the traditionally used fully halogenated chlorocarbons and chlorofluorocarbons have been implicated in causing environmental problems associated with the depletion of the earth's protective ozone layer.
Mathematical models have substantiated that 1-bromopropane will not adversely affect atmospheric chemistry because its contribution to stratospheric ozone depletion and global warming in comparison to the fully halogenated chlorocarbons and chlorofluorocarbons species is negligible. 1-Bromopropane has an ODP of 0.002–0.03 which is significantly lower than the ODPs of 1,1,2-trichloro-1,2,2-trifluoroethane or CFC-113 (0.8) and 1,1-dichloro-1-fluoroethane or HCFC-141b (0.11). The global warming potential (GWP) of 1-bromopropane (0.31) is also significantly lower than CFC-113 (5000) and HCFC-141b (630).
The art has also looked to compositions that include components that contribute additional desired characteristics, such as polar functionality, increased solvency power, and increased stability while retaining those properties exhibited by prior art chlorofluorocarbons including chemical stability, low toxicity, and non-flammability.
It is accordingly an object of this invention to provide novel solvent compositions based on 1-bromopropane and at least one other organic solvent, and which is azeotropic or azeotropic-like compositions, which compositions are useful in solvent and other applications mentioned above.